jtoolman said:
These cheap gram scales are not that accurate along their range from zero to max. give or take! Only a laboratory grade scale would be reliable.
I checked mine against a 4-place Mettler balance (which is accurate to about 0.0002 g), and it's incredibly accurate over the whole range, within one or two numbers in the last digit. It literally could not possibly be any more accurate. It also holds its accuracy without recalibration. It cost about $13 including shipping.
If you really want to check the balance over the whole range, it's not difficult to do. First, get yourself a reference weight to calibrate the balance. For these small electronic scales this is usually an inexpensive 100 g weight. You could skip that step if you want, but it does assure you of some additional accuracy and reproducibility. My balance has held its calibration for months, but it's good to be able to check somehow.
Then you need to test the linearity. The procedure is not hard. This is the classical procedure for calibrating chemical analytical balances and weights. Get yourself some smaller weights (coins will do). Weigh them individually, and then weigh them together in various combinations. You'll want totals spanning the whole range, like 25g, 50g, 75g, etc. (The exact numbers don't matter. It could be 19, 55, etc.) Here's the key: the measured weights should equal the arithmetic sums. Remember that there will be some small roundoff errors. You can reduce the roundoff errors by using a number of small weights and getting many data points.
Overkill? Maybe. As I said, mine is incredibly accurate. But if you do this, you
know there's no error.
